It is becoming increasingly apparent that targeting angiogenesis presents an attractive and certainly wide- ranging therapy for many human diseases ranging from cancer to eye diseases. New pharmacologic therapies to target VEGFR-2 (vascular endothelial growth factor receptor-2) are currently being developed for treatment of several human diseases including, age-related macular degeneration (AMD) and various forms of cancers. It is widely accepted that the angiogenic switch is OFF when the effect of pro-angiogenic molecules such as VEGF and its receptor, VEGFR-2 is balanced by that of anti-angiogenesis molecules, and is ON when the net balance is tipped in favor of angiogenesis. Our recent studies for the first time have identified c-Cbl, ring finger containing ubiquitin E3 ligase as a molecular switch that turns off the angiogenic signaling of VEGFR-2. The goals of this grant application are to investigate role of protein ubiquitination in angiogenesis and the mechanisms involved in this process. In particular, we will investigate role of VEGF-dependent ubiquitination of VEGFR-2, E3 ligases involved in ubiquitination of VEGFR-2, the mechanism by which they are being recruited to VEGFR-2 and sites of ubiquitination will be identified. Moreover, we will address how ubiquitination inhibits PLC-gamma1 activation and investigate its application in angiogenesis. Identification of molecules that negatively regulates VEGFR-2 activation and its signaling partners, thereby targets them for degradation will serve twofold purposes: Unravel the basic mechanisms involved in the negative regulation of angiogenesis. Provide new avenues for development of better and more effective agents to combat angiogenesis-associated diseases. PUBLIC HEALTH RELEVANCE: Angiogenesis, the process by which new blood vessels are formed, is a fundamental pathological condition that contributes to human diseases ranging from diabetic retinopathy and age-related macular degeneration to cancer. Vascular endothelial growth factor (VEGF) and its receptor, VEGFR-2 are responsible for induction of angiogenesis and hence for angiogenesis-associated diseases. Identification of molecules that inhibit the angiogenic signaling of VEGFR-2 will provide new avenues for development of better and more effective agents to combat angiogenesis-associated diseases.